Two software packages have been designed and implemented to enable interactive analysis of images of cardiac muscle tissue for the following purposes: 1. To determine percentages of myocardial fibrosis in patients with ventricular hypertrophy and in animals with experimental ventricular hypertrophy from tissues differentially stained to distinguish fibrous tissue from cardiac muscle cells. 2. To measure morphometric features of cardiac muscle tissue from photomicrographs, including cell areas, cell perimeters, capillary densities, nuclei densities, capillary spacing, percent cell areas, and percent interstitium. Both packages are fully operational and images of specimens may be processed. We anticipate that the correlation of derived morphometric image data with other data (clinical, hemodynamic, long-term follow-up, etc.), associated with the corresponding subjects will reveal useful information underlying certain cardiac disease processes as well as providing additional useful indices for clinical decision-making.